A method for preparing a metal molecular catalyst polymer electrode and a method for preparing 1,2-propanediol using the same

Abstract

The application provides a preparation method of a metal molecular catalyst polymer electrode and a method for preparing 1,2-propanediol by using the same. The metal molecular catalyst polymer electrode comprises an anode catalyst substrate, a polymer formed by polymerization of an organic ligand molecule containing a heterocycle, and an active metal coordinated with the polymer, wherein the organic ligand molecule comprises a polymerization unit, a connecting unit and a coordination unit, and the organic ligand molecule is combined with the active metal to form a complex through a coordination bond formed by the coordination unit. The metal molecular catalyst polymer electrode is prepared by an electrochemical oxidative polymerization method. The electrochemical oxidative polymerization method realizes controllable synthesis of a high-load molecular catalyst polymer electrode, can realize high adjustability of the structure of the polymerization unit and the coordination unit in the molecular catalyst without affecting the catalyst load, and further realizes rational regulation of the catalytic activity of the active metal center.

Description

Technical Field

[0001] This invention relates to a method for preparing a polymer electrode of a metal molecule catalyst and a method for preparing 1,2-propanediol using the same, belonging to the field of electrocatalytic organic synthesis technology. Background Technology

[0002] As the core of the petrochemical industry, propylene is an important basic chemical raw material. In recent years, the scale of new propylene production capacity worldwide has repeatedly reached record highs, with global propylene capacity increasing by 5.5% year-on-year in 2023. However, with the propylene self-sufficiency rate increasing year by year, the actual growth rate of propylene capacity expansion far exceeds the growth rate of consumption. As the supply-side pressure on propylene further intensifies, the diversification of market demand for its downstream products is of great significance for promoting the development of propylene conversion processes and pathways to other chemicals, thereby driving increased consumption demand.

[0003] Due to the slowdown in the growth rates of industries such as food delivery and automobiles in the past two years, the proportion of polypropylene in propylene consumption has declined. Meanwhile, propylene oxide, propylene glycol, acrylonitrile, and acetone have become the main drivers of the recovery in consumption growth. Propylene oxide is mainly used to produce polyether polyols, propylene glycol, and various nonionic surfactants, and is widely used in the petroleum, chemical, pesticide, textile, and daily chemical industries. Its hydrolysis product, 1,2-propanediol, is mainly used in surface coatings and reinforced plastics, and is also widely used in the food and pharmaceutical industries as a hygroscopic agent, antifreeze, lubricant, and solvent.

[0004] However, the propylene industry, including its production and conversion processes, is considered an energy-intensive industry. In the industrial chain of olefin oxidation, thermocatalytic conversion is currently the dominant mode. The process for producing propylene oxide from propylene mainly uses the traditional chlorohydrin process and co-oxidation process. 1,2-Propanediol is primarily obtained by hydrolyzing propylene oxide, a hydrolysis reaction that requires high temperature or strong acidity, making the reaction conditions quite harsh. Furthermore, the chlorohydrin process involves propylene chlorohydrinization, lime milk saponification, and product refining, consuming large amounts of water and chlorine, causing severe equipment corrosion, and generating large quantities of wastewater and waste residue, leading to serious environmental and safety problems. The co-oxidation process requires the production of peroxides as oxidants for olefins, facing challenges such as high temperature and pressure, complex processes, high costs, safety hazards, and high carbon emissions.

[0005] Therefore, developing novel olefin catalytic oxidation strategies and promoting energy-saving and emission-reducing low-carbon propylene technology innovation will bring considerable sustainable development value to the propylene industry. Among these, electrocatalytic olefin oxidation driven by renewable energy is a greener, cleaner, and more efficient strategy with enormous industrial application potential. In recent years, relevant literature has reported methods for the direct electrocatalytic oxidation of propylene to prepare propylene oxide and 1,2-propanediol using transition metal catalysts.

[0006] Reference 1 discloses a supported silver-based molecular catalyst and its application in the preparation of 1,2-propanediol. This catalyst consists of a silver salt and a pyrazole compound forming a complex, which is then supported on a carrier. It is used to catalyze the direct oxidation of propylene to 1,2-propanediol, exhibiting high selectivity and good stability. However, its electrocatalytic faradaic efficiency remains low, rarely reaching 20%, and the current density is also low. Furthermore, increasing the current density leads to a decrease in faradaic efficiency, significantly reducing energy utilization efficiency.

[0007] Reference 2 discloses a silver single-atom catalyst and its application in the preparation of 1,2-propanediol. Although this catalyst exhibits high Faradaic efficiency in the electrocatalytic oxidation of propylene to 1,2-propanediol, it suffers from low metal active site loading and persistent low current density.

[0008] In summary, existing methods for the electrocatalytic oxidation of propylene to 1,2-propanediol have many problems. Although supported molecular catalysts have shown some catalytic activity in the electrocatalytic oxidation of propylene, the limited number of catalytic active sites in existing supported methods leads to low current density, low Faradaic efficiency, and reduced energy utilization efficiency in the catalytic process.

[0009] References:

[0010] Reference 1: CN116356360A

[0011] Reference 2: CN116254565A Summary of the Invention

[0012] The problem the invention aims to solve

[0013] To address the aforementioned problems, this invention aims to provide a method for preparing a polymer electrode of a metal molecular catalyst. This method employs an electrochemical oxidative polymerization process to achieve the controllable synthesis of a polymer electrode with a high loading of molecular catalyst. It can achieve a high degree of tunability of the structure of polymerization units and coordination units in the molecular catalyst without affecting the catalyst loading, thereby enabling rational regulation of the catalytic activity of the active metal center.

[0014] Furthermore, this invention also provides a method for preparing 1,2-propanediol by propylene oxidation using an electropolymerization molecular catalyst. This method utilizes a metal molecular catalyst polymer electrode prepared by the above-mentioned method as the anode to prepare 1,2-propanediol via electrocatalytic propylene oxidation. The reaction process is simple, mild, environmentally friendly, and suitable for industrial production. This method exhibits high current density, high Faradaic efficiency, high energy utilization efficiency, and a relatively high production rate at room temperature and atmospheric pressure. Simultaneously, the method is mild, environmentally friendly, and low-cost, making it suitable for industrial production.

[0015] Solution for solving the problem

[0016] This invention first provides a method for preparing a metal molecule catalyst polymer electrode, wherein the metal molecule catalyst polymer electrode comprises an anode catalyst substrate, a polymer formed by polymerization of heterocyclic organic ligand molecules, and an active metal coordinated with the polymer, wherein the organic ligand molecule comprises a polymerization unit, a linking unit, and a coordination unit, and the organic ligand molecule forms a coordination bond with the active metal through the coordination unit to obtain a complex. The preparation method includes the following steps:

[0017] S1: The synthesis of organic ligand monomers is achieved by connecting polymerization units and coordination units with saturated alkyl chains through nucleophilic substitution reactions.

[0018] S2: Organic polymer electrode is obtained by oxidizing and polymerizing organic ligand monomers via electrochemical oxidation and loading them onto the surface of the anode catalyst substrate;

[0019] S3: The organic polymer electrode is subjected to a coordination reaction with a metal salt solution to obtain a metal molecular catalyst polymer electrode.

[0020] According to the preparation method of the present invention, the anode catalyst substrate includes one or more of carbon cloth, carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass and FTO conductive glass, preferably carbon cloth or carbon paper.

[0021] According to the preparation method of the present invention, the polymerization unit includes one or more of thiophene, pyrrole, 3,4-ethylenedioxythiophene, furan, indole, aniline, 9-fluorenic acid, carbazole, and benzothiophene, preferably one or more of furan, indole, or carbazole;

[0022] The coordination unit includes one or more of oxazoline ligands, Salen ligands, polypyridine ligands, phenanthroline ligands, and bipyridine ligands, preferably oxazoline ligands and / or bipyridine ligands;

[0023] The saturated alkyl chain includes a straight-chain saturated alkyl chain of C1 to C10.

[0024] According to the preparation method of the present invention, the active metal includes one or more of iron, cobalt, manganese, nickel, copper, silver, gold, iridium, palladium, and platinum, preferably silver and / or palladium.

[0025] According to the preparation method of the present invention, wherein the electrochemical oxidation method in step S2 includes: in a separated cell, using an anode catalyst substrate as an anode, a cathode catalyst as a cathode, and a solution containing a supporting electrolyte as an electrolyte, adding the organic ligand monomer to the anode cell to carry out an oxidative polymerization reaction and loading it onto the surface of the anode catalyst substrate to obtain an organic polymer electrode.

[0026] Preferably, the concentration of the organic ligand monomer is 0.005–0.015 mol / L;

[0027] The electrolyte includes one or more of tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate, and tetrabutylammonium hexafluorophosphate in acetonitrile or dichloromethane solution, preferably a tetrabutylammonium perchlorate in acetonitrile solution;

[0028] The cathode catalyst comprises one or more of platinum, gold, silver, ruthenium, iridium, palladium, copper, and rhodium, with platinum being preferred;

[0029] The current density during the oxidative polymerization reaction is 0.1–2.5 mA / cm². 2 .

[0030] According to the preparation method of the present invention, in step S3, the metal salt solution comprises an acetonitrile or dichloromethane solution of the metal salt.

[0031] Preferably, the concentration of the metal salt solution is 5–15 mmol / L;

[0032] The molar ratio of the active metal to the organic ligand molecule is 2:1 to 10:1.

[0033] In the aforementioned metal molecule catalyst polymer electrode, the loading of the active metal is 0.1–5 μmol / cm³. 2 .

[0034] This invention also provides a method for preparing 1,2-propanediol by propylene oxidation using an electropolymerization molecular catalyst, wherein the following steps are included: using a metal molecular catalyst polymer electrode prepared by the method described in this invention as the anode, using a cathode catalyst as the cathode, assembling an electrolytic cell with an electrolyte aqueous solution, and introducing propylene gas into the electrolytic cell under voltage conditions.

[0035] According to the method of the present invention, the electrolytic cell further comprises a reference electrode, wherein the reference electrode is Ag / AgCl or Hg / Hg2Cl2, preferably Ag / AgCl;

[0036] The voltage is 1V to 4V vs Ag / AgCl, preferably 1.4V to 2.0V vs Ag / AgCl, and more preferably 1.6V to 2.0V vs Ag / AgCl.

[0037] According to the method of the present invention, the electrolyte aqueous solution comprises one or more aqueous solutions selected from sodium sulfate, potassium sulfate, lithium sulfate, zinc sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, lithium nitrate, zinc nitrate, calcium nitrate, magnesium nitrate, aluminum nitrate, sulfuric acid, nitric acid, perchloric acid, sodium perchlorate, potassium perchlorate, and lithium perchlorate.

[0038] Preferably, the concentration of the electrolyte aqueous solution is 1 mg / mL to 1000 mg / mL, more preferably 3 mg / mL to 20 mg / mL.

[0039] According to the method of the present invention, the flow rate of the propylene gas is 1 s.ccm to 500 s.ccm, preferably 10 s.ccm to 30 s.ccm.

[0040] The effects of the invention

[0041] The technical effects of this invention are as follows:

[0042] 1. This invention is the first to use an electrochemical oxidative polymerization method to prepare a polymer electrode for a metal molecular catalyst, breaking the basic pattern of traditional carbon-supported molecular catalysts and realizing the preparation and synthesis of a polymer electrode with a high loading capacity of molecular catalysts with tunable structure.

[0043] 2. The metal molecular catalyst polymer electrode prepared by this invention has a large current density for propylene oxidation to 1,2-propanediol, and a high Faraday efficiency of over 40%. It has high energy utilization efficiency and a high reaction rate, making it suitable for the industrial production of 1,2-propanediol.

[0044] 3. The preparation method of 1,2-propanediol provided by this invention is mild and can be carried out at room temperature and normal pressure. No special reagents or special conditions are required. While reducing the emission of waste gases such as carbon dioxide, hydrogen can also be generated at the cathode, which is both green and environmentally friendly and improves economic efficiency. Attached Figure Description

[0045] Figure 1 This is a structural diagram of the polymer electrode of the metal molecular catalyst of the present invention and a process diagram of the preparation of 1,2-propanediol by electrocatalytic oxidation of propylene using the molecular catalyst.

[0046] Figure 2 This is a schematic diagram of the synthesis method of organic ligand monomers, using carbazole as the polymerization unit and 4,4'-dimethyl-2,2'-bipyridine as the coordination unit as an example;

[0047] Figure 3 The results are obtained by liquid chromatography testing of the catalyst synthesized under an oxidation current of 0.25 mA and a constant voltage of 1.8 V for 1 hour in Example 1 of the present invention.

[0048] Figure 4 The current-time curve of the catalyst synthesized in Example 1 of the present invention reacting at a constant voltage of 1.8V for 1 hour to electrocatalyze the oxidation of propylene to 1,2-propanediol.

[0049] Figure 5 The results are obtained by liquid chromatography testing of the catalyst synthesized under an oxidation current of 0.5 mA and a constant voltage of 1.8 V for 1 hour in Example 2 of the present invention.

[0050] Figure 6 The results are obtained by liquid chromatography testing of the catalyst synthesized under an oxidation current of 1.0 mA and a constant voltage of 1.8 V for 1 hour in Example 3 of the present invention.

[0051] Figure 7 The results are obtained by liquid chromatography testing of the catalyst synthesized under an oxidation current of 1.5 mA and a constant voltage of 1.8 V for 1 hour in Example 4 of the present invention.

[0052] Figure 8 The results are obtained by liquid chromatography testing of the catalyst synthesized under an oxidation current of 2.0 mA and a constant voltage of 1.8 V for 1 hour in Example 5 of the present invention.

[0053] Figure 9 This paper illustrates the effect of the oxidation current density of the electropolymerization catalyst on the reaction performance of the electrocatalytic oxidation of propylene to 1,2-propanediol in Examples 1-5 of the present invention; wherein, the bar graph represents the Faraday efficiency, and the line graph represents the partial current density.

[0054] Figure 10 The results of liquid chromatography analysis of the catalyst synthesized in Example 6 of this invention, which uses indole as the polymerization unit and 4,4'-dimethyl-2,2'-bipyridine as the coordination unit, and reacted at a constant voltage of 1.8V for 1 hour, are based on the ligand monomer.

[0055] Figure 11The results of liquid chromatography analysis of the catalyst synthesized in Example 7 of this invention, based on the ligand monomer synthesized with carbazole as the polymerization unit and 4-dimethyl-2,2'-bipyridine as the coordination unit, were obtained after reacting at a constant voltage of 1.8V for 1 hour.

[0056] Figure 12 The results are obtained by liquid chromatography of the carbon-supported molecular catalyst used in Comparative Example 1 of this invention, reacting at a constant voltage of 1.8V for 1 hour.

[0057] Figure 13 This is the current-time curve of the catalyst synthesized in Comparative Example 1 of the present invention reacting at a constant voltage of 1.8V for 1 hour to electrocatalyze the oxidation of propylene to 1,2-propanediol. Detailed Implementation

[0058] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0059] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0060] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0061] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0062] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0063] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0064] In this specification, the range of values ​​referred to as "value A and above" refers to the range including the endpoint value A.

[0065] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15℃ to 30℃, or more specifically 15℃ to 25℃, such as 20℃.

[0066] In this manual, "atmospheric pressure" is used to refer to one standard atmosphere, which can be 101.3 kPa.

[0067] <First Aspect>

[0068] A first aspect of the present invention provides a method for preparing a metal molecule catalyst polymer electrode, wherein the metal molecule catalyst polymer electrode comprises an anode catalyst substrate, a polymer formed by polymerization of a monomer containing a heterocyclic organic ligand molecule, and an active metal coordinated with the polymer, wherein the organic ligand molecule comprises a polymerization unit, a linking unit, and a coordination unit, and the organic ligand molecule forms a coordination bond with the active metal through the coordination unit to obtain a complex. The preparation method includes the following steps:

[0069] S1: The synthesis of organic ligand monomers is achieved by connecting polymerization units and coordination units with saturated alkyl chains through nucleophilic substitution reactions.

[0070] S2: Organic polymer electrode is obtained by oxidizing and polymerizing organic ligand monomers via electrochemical oxidation and loading them onto the surface of the anode catalyst substrate;

[0071] S3: The organic polymer electrode is subjected to a coordination reaction with a metal salt solution to obtain a metal molecular catalyst polymer electrode.

[0072] This invention constructs an organic ligand molecule comprising polymerization units, linking units, and coordination units. The polymerization units can polymerize during electro-oxidative polymerization and be loaded onto the anode surface. Simultaneously, the coordination units form coordination bonds with an active metal to form a complex, thereby obtaining a metal molecule catalyst polymer electrode. A schematic diagram of its structure is shown below. Figure 1 As shown, N represents the coordination unit and M represents the active metal. This method can improve the catalyst loading while achieving tunability of the molecular catalyst microstructure.

[0073] Step S1

[0074] Step S1 of the present invention is a step of synthesizing organic ligand molecule monomers, wherein the organic ligand molecule includes a polymerization unit, a linking unit and a coordination unit, and the synthesis step may include connecting the polymerization unit and the coordination unit through the linking unit to realize the synthesis of organic ligand molecule monomers.

[0075] In some specific embodiments, the polymerization unit may include one or more of thiophene, pyrrole, 3,4-ethylenedioxythiophene, furan, indole, aniline, 9-fluorenic acid, carbazole, and benzothiophene, preferably one or more of furan, indole, or carbazole.

[0076] In some specific implementations, the coordination unit may include one or more of oxazoline ligands, Salen ligands, polypyridine ligands, phenanthroline ligands, and bipyridine ligands, preferably oxazoline ligands and / or bipyridine ligands.

[0077] There is no particular limitation on the type of linking unit, as long as it can connect the polymerization unit and the coordination unit. In some specific embodiments, the linking unit can be a saturated alkyl chain, such as a C1-C10 straight-chain saturated alkyl chain. In some more advanced embodiments, the material providing the linking unit includes halides containing saturated alkyl chains, such as 1,2-dichloroethane, 1,4-dichlorobutane, 1,6-dichlorohexane, etc.

[0078] In some specific implementations, in the step of synthesizing the organic ligand monomer, the molar ratio of the polymerization unit to the linking unit is 0.95:1 to 1.05:1, for example, it can be 0.98:1, 1:1, 1.02:1, etc., and the molar ratio of the polymerization unit to the coordination unit is 0.95:1 to 1.05:1, for example, it can be 0.98:1, 1:1, 1.02:1, etc.

[0079] The method for synthesizing the organic ligand monomer can employ nucleophilic substitution to link the polymerization unit and the coordination unit through a linking unit, thereby synthesizing the organic ligand monomer. In some specific embodiments, using carbazole as the polymerization unit, an ethyl chain as the linking unit, and a bipyridine ligand as the coordination unit as an example, the steps for synthesizing the organic ligand molecule include: using carbazole and 1,2-dichloroethane as substrates, sodium hydride as a base, and tetrahydrofuran as a solvent, a nucleophilic substitution reaction is first used to link carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) (first step); based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates, potassium tert-butoxide as a base, and tetrahydrofuran as a solvent, a nucleophilic substitution reaction is then used to link bipyridine (coordination unit) and the linking unit, completing the synthesis of the organic ligand monomer (the specific reaction process is as follows). Figure 2 (As shown).

[0080] Step S2

[0081] Step S2 of the present invention is a polymerization step of organic ligand monomers. The organic ligand monomers obtained above are polymerized by electrochemical oxidation and loaded onto the surface of the anode catalyst substrate to obtain an organic polymer electrode.

[0082] In some specific embodiments, the electrochemical oxidation method includes: in a separated cell, using an anode catalyst substrate as the anode, a cathode catalyst as the cathode, and a solution containing a supporting electrolyte as the electrolyte, adding the organic ligand monomer to the anode cell to carry out an oxidative polymerization reaction and loading it onto the surface of the anode catalyst substrate to obtain an organic polymer electrode.

[0083] In some specific embodiments, the anode catalyst substrate may include one or more of the following: carbon cloth, carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass, and FTO conductive glass, wherein carbon cloth or carbon paper is preferred.

[0084] In some specific implementations, the concentration of the organic ligand monomer can be 0.005 to 0.015 mol / L, for example, 0.007 mol / L, 0.009 mol / L, 0.01 mol / L, 0.012 mol / L, 0.014 mol / L, etc.

[0085] In some specific embodiments, the electrolyte may include one or more of tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate, and tetrabutylammonium hexafluorophosphate in acetonitrile or dichloromethane solution, wherein a tetrabutylammonium perchlorate in acetonitrile solution is preferred; the concentration of the electrolyte may be 0.05 to 0.15 mol / L, for example, 0.07 mol / L, 0.09 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, etc.

[0086] In some specific embodiments, the cathode catalyst includes one or more of platinum, gold, silver, ruthenium, iridium, palladium, copper, and rhodium, with platinum being a preferred material.

[0087] In some specific embodiments, the current density during the oxidative polymerization reaction is 0.1–2.5 mA / cm². 2 For example, it can be 0.12 mA / cm 2 0.15mA / cm 2 0.17mA / cm 2 0.2mA / cm 2 0.22mA / cm 2 wait.

[0088] The present invention does not have any particular limitation on the partitioned pool, and it can be selected as needed, such as a partitioned H-type pool, etc.

[0089] In some more specific embodiments, a reference electrode is also present in the electrolytic cell of the electrochemical oxidation method, and the preferred reference electrode is a silver / silver ion electrode.

[0090] In some specific implementations, the electrochemical oxidation time can be 100 to 2000 s, for example, 200 s, 500 s, 1000 s, 1500 s, 2000 s, etc.

[0091] Step S3

[0092] Step S3 of the present invention is the step of polymer coordination of active metal formed by the polymerization of organic ligand molecules. Specifically, the organic polymer electrode is subjected to a coordination reaction with a metal salt solution to obtain a metal molecule catalyst polymer electrode.

[0093] In some specific embodiments, the active metal may include one or more of iron, cobalt, manganese, nickel, copper, silver, gold, iridium, palladium, and platinum, wherein silver and / or palladium may be preferred.

[0094] In some specific embodiments, the metal salt solution is an acetonitrile or dichloromethane solution containing the metal salt. The present invention does not particularly limit the type of metal salt, such as nitrates or sulfates of the above-mentioned active metals, with nitrates being preferred.

[0095] In some preferred embodiments, the concentration of the metal salt solution can be 5 to 15 mmol / L, for example, 7 mmol / L, 9 mmol / L, 10 mmol / L, 12 mmol / L, 14 mmol / L, etc.

[0096] In some specific embodiments, the molar ratio of the active metal to the organic ligand is 2:1 to 10:1, for example, it can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc.; the loading of the active metal center in the metal molecule catalyst polymer electrode is 0.1 to 5 μmol / cm³. 2 Preferably 1–5 μmol / cm 2 For example, it can be 1 μmol / cm 2 1.5 μmol / cm 2 2μmol / cm 2 2.5 μmol / cm 2 3μmol / cm 2 3.5 μmol / cm 24μmol / cm 2 4.5 μmol / cm 2 wait.

[0097] In some specific implementations, the coordination reaction time can be 6 to 12 hours, for example, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, etc.

[0098] Other steps

[0099] The preparation method of the present invention may further include post-processing steps such as washing and drying.

[0100] In some specific embodiments, after obtaining the organic polymer electrode by electrochemical oxidation, the step may further include rinsing the organic polymer electrode with an organic solvent such as acetonitrile or dichloroethane.

[0101] In some other specific embodiments, after obtaining the metal molecular catalyst polymer electrode by polymer coordination of the active metal, a washing and drying step may be included. Specifically, the metal molecular catalyst polymer electrode may be rinsed with acetonitrile and then vacuum dried.

[0102] <Second aspect>

[0103] The second aspect of the present invention provides a method for preparing 1,2-propanediol by oxidizing propylene using an electropolymerized molecular catalyst, comprising the following steps: using a metal molecular catalyst polymer electrode prepared by the preparation method described in the first aspect as the anode, using a cathode catalyst as the cathode, assembling an electrolytic cell with an electrolyte aqueous solution, and introducing propylene gas into the electrolytic cell under voltage conditions.

[0104] For a detailed schematic diagram of the preparation method of 1,2-propanediol of the present invention, please refer to [the original text]. Figure 1 .

[0105] In some specific embodiments, the cathode catalyst includes one or more of platinum, gold, silver, ruthenium, iridium, palladium, copper, and rhodium, with platinum being a preferred material.

[0106] In some specific implementations, the electrolytic cell also has a reference electrode, which is Ag / AgCl or Hg / Hg2Cl2, preferably Ag / AgCl.

[0107] In some specific implementations, the voltage is 1V to 4V vs Ag / AgCl, preferably 1.4V to 2.0V vs Ag / AgCl, more preferably 1.6V to 2.0V vs Ag / AgCl, for example, it can be 1.5V vs Ag / AgCl, 1.6V vs Ag / AgCl, 1.7V vs Ag / AgCl, 1.8V vs Ag / AgCl, 1.9V vs Ag / AgCl, 2.0V vs Ag / AgCl, etc.

[0108] In some specific embodiments, the electrolyte aqueous solution may include one or more aqueous solutions selected from sodium sulfate, potassium sulfate, lithium sulfate, zinc sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, lithium nitrate, zinc nitrate, calcium nitrate, magnesium nitrate, aluminum nitrate, sulfuric acid, nitric acid, perchloric acid, sodium perchlorate, potassium perchlorate, and lithium perchlorate.

[0109] In some preferred embodiments, the concentration of the electrolyte aqueous solution can be from 1 mg / mL to 1000 mg / mL, preferably from 3 mg / mL to 20 mg / mL, for example, it can be 2 mg / mL, 6 mg / mL, 10 mg / mL, 12 mg / mL, 14 mg / mL, 16 mg / mL, 20 mg / mL, 50 mg / mL, 100 mg / mL, 200 mg / mL, 500 mg / mL, 800 mg / mL, etc.

[0110] In some specific implementations, the flow rate of the propylene gas is 1 s.ccm to 500 s.ccm, preferably 10 s.ccm to 30 s.ccm, for example, it can be 15 s.ccm, 20 s.ccm, 25 s.ccm, 50 s.ccm, 100 s.ccm, 200 s.ccm, 300 s.ccm, 400 s.ccm, etc.

[0111] In this invention, a reaction can occur by introducing propylene gas into an electrolyte aqueous solution. Propylene gas is continuously introduced during the reaction process. Therefore, the gas introduction time in this invention is also the reaction time.

[0112] In some specific implementations, the reaction time of the present invention can be 0.5h to 48h, preferably 0.5h to 24h, for example, 1h, 2h, 3h, 4h, 6h, 8h, 10h, 16h, 20h, 30h, 40h, etc.

[0113] In this invention, the reaction conditions for preparing 1,2-propanediol by polymer electrocatalysis using metal molecular catalysts are mild and can be carried out at room temperature and normal pressure. If the solubility of certain silver salts in electrolyte aqueous solution is low at room temperature, the temperature of the electrolyte aqueous solution can be appropriately increased to increase the solubility of silver salts and thus increase the concentration of silver ions in the electrolyte aqueous solution.

[0114] In this invention, "PG" refers to 1,2-propanediol, and "propanediol" also refers to 1,2-propanediol.

[0115] In some preferred embodiments, the shunt current density for preparing 1,2-propanediol using the method of the present invention can be 6 mA·cm⁻¹. -2 The preferred value is 6.5 mA·cm. -2 The above is preferred, 7mA·cm -2 The above; the Faraday efficiency can be 40% or more, preferably 44% or more, more preferably 46% or more; the reaction rate can be 110 μmol·h⁻¹ -1 ·cm -2 The preferred concentration is 120 μmol·h⁻¹. -1 ·cm -2 The above, more preferably 130 μmol·h -1 ·cm -2 above.

[0116] Quantitative identification and detection of products

[0117] In this invention, the quantitative identification of the product 1,2-propanediol can be achieved by liquid chromatography. In some embodiments, the detection conditions for liquid chromatography can be as follows: the detector is a differential refractive index detector (RID), the mobile phase is a 5 mM sulfuric acid aqueous solution, and the flow rate is 0.6 mL / min. In some specific embodiments of this invention, the retention time of 1,2-propanediol in the liquid chromatogram is 16.4 min (which can fluctuate within a reasonable range, such as 16.4 ± 0.2 min or 16.4 ± 0.1 min).

[0118] Example

[0119] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0120] The detection conditions for liquid chromatography in the examples are as follows: the detector is a differential refractive index detector (RID), the mobile phase is 5 mM sulfuric acid aqueous solution, and the flow rate is 0.6 mL / min.

[0121] Test method for active metal loading: The silver content was quantitatively tested using ICP-OES with argon as the carrier gas.

[0122] Example 1

[0123] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0124] S1: Using carbazole and 1,2-dichloroethane as substrates (molar ratio of carbazole to 1,2-dichloroethane is 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) are first linked via nucleophilic substitution reaction (first step). Based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates (molar ratio of 4,4'-dimethyl-2,2'-bipyridine to carbazole is 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the bipyridine (coordination unit) and linking unit are linked via nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0125] S2: In a partitioned H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode. At 0.25 mA / cm²... 2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0126] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0127] The silver metal loading of the polymer electrode with the metal molecular catalyst obtained by testing was 1.9 μmol / cm³. 2 .

[0128] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0129] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 3 As shown, the peak area of ​​1,2-propanediol is 57236.5, the Faraday efficiency of 1,2-propanediol is 48.8%, and the PG partial current density is 7.9 mA·cm. -2 The reaction rate is 147.4 μmol·h⁻¹ -1 ·cm -2 .

[0130] In addition, the current-time curves for the electrocatalytic oxidation of propylene to 1,2-propanediol were measured, and the results are as follows: Figure 4 As shown in the figure, the reaction current increases continuously as the reaction proceeds.

[0131] Example 2

[0132] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0133] S1: Using carbazole and 1,2-dichloroethane as substrates (molar ratio of carbazole to 1,2-dichloroethane is 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the first step is to achieve the connection between carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) through a nucleophilic substitution reaction. Based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates (molar ratio of 4,4'-dimethyl-2,2'-bipyridine to carbazole is 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the connection between bipyridine (coordination unit) and the linking unit is achieved through a nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0134] S2: In a partitioned H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode. At 0.5 mA / cm²... 2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0135] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0136] The silver metal loading of the polymer electrode with the metal molecular catalyst obtained by testing was 1.8 μmol / cm³. 2 .

[0137] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0138] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 5 As shown, the peak area of ​​1,2-propanediol is 56872.6, the Faraday efficiency of 1,2-propanediol is 46.1%, and the PG partial current density is 7.9 mA·cm. -2 The reaction rate is 146.4 μmol·h⁻¹ -1 ·cm -2 .

[0139] Example 3

[0140] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0141] S1: Using carbazole and 1,2-dichloroethane as substrates (molar ratio of carbazole to 1,2-dichloroethane is 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the first step is to achieve the connection between carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) through a nucleophilic substitution reaction. Based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates (molar ratio of 4,4'-dimethyl-2,2'-bipyridine to carbazole is 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the connection between bipyridine (coordination unit) and the linking unit is achieved through a nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0142] S2: In a separated H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode. At 1.0 mA / cm²...2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0143] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0144] The silver metal loading of the polymer electrode with the metal molecular catalyst obtained by testing was 1.6 μmol / cm³. 2 .

[0145] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0146] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 6 As shown, the peak area of ​​1,2-propanediol is 47267.4, the Faraday efficiency of 1,2-propanediol is 46.9%, and the PG partial current density is 6.5 mA·cm. -2 The reaction rate is 121.7 μmol·h⁻¹ -1 ·cm -2 .

[0147] Example 4

[0148] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0149] S1: Using carbazole and 1,2-dichloroethane as substrates (molar ratio of carbazole to 1,2-dichloroethane is 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the first step is to achieve the connection between carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) through a nucleophilic substitution reaction. Based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates (molar ratio of 4,4'-dimethyl-2,2'-bipyridine to carbazole is 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the connection between bipyridine (coordination unit) and the linking unit is achieved through a nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0150] S2: In a separated H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode, at 1.5 mA / cm². 2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0151] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0152] The tested silver metal loading of the polymer electrode with the metal molecular catalyst was 1.5 μmol / cm³. 2 .

[0153] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0154] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 7 As shown, the peak area of ​​1,2-propanediol is 46393.7, the Faraday efficiency of 1,2-propanediol is 47.2%, and the PG partial current density is 6.4 mA·cm⁻¹. -2 The reaction rate is 119.5 μmol·h⁻¹ -1 ·cm -2 .

[0155] Example 5

[0156] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0157] S1: Using carbazole and 1,2-dichloroethane as substrates (molar ratio of carbazole to 1,2-dichloroethane is 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the first step is to achieve the connection between carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) through a nucleophilic substitution reaction. Based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates (molar ratio of 4,4'-dimethyl-2,2'-bipyridine to carbazole is 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the connection between bipyridine (coordination unit) and the linking unit is achieved through a nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0158] S2: In a separated H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode, at 2.0 mA / cm². 2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0159] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0160] The tested silver metal loading of the polymer electrode with the metal molecular catalyst was 1.7 μmol / cm³. 2 .

[0161] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0162] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 8 As shown, the peak area of ​​1,2-propanediol is 46961.3, the Faraday efficiency of 1,2-propanediol is 44.9%, and the PG partial current density is 6.5 mA·cm. -2 The reaction rate is 120.9 μmol·h⁻¹ -1 ·cm -2 .

[0163] Examples 1-5 determined the effect of the constant current of the polymer electrode used to prepare the metal molecular catalyst on the electrocatalytic oxidation of propylene to 1,2-propanediol. The results are shown in [reference needed]. Figure 9 .from Figure 9 It can be seen that within the range of 0.25mA-2.0mA, it exhibits high Faraday efficiency and high partial current density.

[0164] Example 6

[0165] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0166] S1: Using indole and 1,2-dichloroethane as substrates (molar ratio of indole to 1,2-dichloroethane 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the linking of indole (polymerization unit) and 1,2-dichloroethane (linking unit) is first achieved through a nucleophilic substitution reaction (first step). Based on this, using the product obtained in the first step and 4,4'-dimethyl-2,2'-bipyridine as substrates (molar ratio of 4,4'-dimethyl-2,2'-bipyridine to indole 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the linking of bipyridine (coordination unit) and the linking unit is achieved through a nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0167] S2: In a partitioned H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode. At 0.5 mA / cm²... 2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0168] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0169] The silver metal loading of the polymer electrode with the metal molecular catalyst obtained by testing was 1.8 μmol / cm³. 2 .

[0170] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0171] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 10 As shown, the peak area of ​​1,2-propanediol is 37674.1, the Faraday efficiency of 1,2-propanediol is 36.2%, and the PG partial current density is 5.2 mA·cm⁻¹. -2 The reaction rate is 100.4 μmol·h⁻¹ -1 ·cm -2 .

[0172] Example 7

[0173] (1) 1cm 2 Preparation of polymer electrodes with metal molecular catalysts:

[0174] S1: Using carbazole and 1,2-dichloroethane as substrates (molar ratio of carbazole to 1,2-dichloroethane is 1:1), sodium hydride as base, and tetrahydrofuran as solvent, the first step is to achieve the connection between carbazole (polymerization unit) and 1,2-dichloroethane (linking unit) through a nucleophilic substitution reaction. Based on this, using the product obtained in the first step and 4-methyl-2,2'-bipyridine as substrates (molar ratio of 4-methyl-2,2'-bipyridine to carbazole is 1:1), potassium tert-butoxide as base, and tetrahydrofuran as solvent, the connection between bipyridine (coordination unit) and the linking unit is achieved through a nucleophilic substitution reaction, thus completing the synthesis of the organic ligand monomer.

[0175] S2: In a partitioned H-cell, add 5 mL of 0.1 M tetrabutylperchlorate ammonium acetonitrile solution to both the cathode and anode. Add 50 μmol of organic ligand molecules to the anode solution and stir the solution thoroughly. Use carbon paper and platinum sheet as the anode and cathode, respectively, and a silver / silver ion electrode as the reference electrode. At 0.5 mA / cm²... 2 The oxidative polymerization of organic ligand molecules was carried out under a constant oxidative current density to prepare and synthesize 1cm... 2 An organic polymer electrode was used. After reacting for 1000 s, the organic polymer electrode was rinsed with acetonitrile.

[0176] S3: The organic polymer electrode was completely immersed in an acetonitrile solution containing 10 mM silver nitrate, stirred overnight, rinsed with acetonitrile, and dried under vacuum to obtain a metal molecular catalyst polymer electrode.

[0177] The silver metal loading of the polymer electrode with the metal molecular catalyst obtained by testing was 1.9 μmol / cm³. 2 .

[0178] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0179] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. A three-electrode system was constructed, using a metal molecular catalyst polymer electrode as the anode, a platinum sheet as the cathode, and an Ag / AgCl electrode as the reference electrode. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode. Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 11 As shown, the peak area of ​​1,2-propanediol is 45364.1, the Faraday efficiency of 1,2-propanediol is 36.2%, and the PG partial current density is 6.3 mA·cm. -2 The reaction rate is 116.8 μmol·h⁻¹ -1 ·cm -2 .

[0180] Comparative Example 1

[0181] (1) Preparation of carbon-supported molecular catalyst electrode:

[0182] A 40 mL DMF solution containing 3 mg of silver-4,4'-dimethyl-2,2'-bipyridine complex (Ag-bpy Me2) as a molecular catalyst and 30 mg of activated carbon as a carbon support was prepared. The solution was mixed and sonicated at room temperature for 30 min, followed by stirring for 24 h to load the catalyst. After loading, the supernatant was removed by centrifugation, and the catalyst was washed repeatedly with ethanol and deionized water, centrifuged again, and dried. The resulting catalyst was then dried overnight in a vacuum oven to obtain the carbon-supported silver complex. The silver metal loading of the polymer electrode obtained by the metal molecular catalyst was measured to be 0.8 μmol / cm³. 2 .

[0183] (2) Electrocatalytic oxidation of propylene to prepare 1,2-propanediol:

[0184] A 40 mL aqueous solution containing 0.56 g sodium perchlorate was prepared as the electrolyte. The obtained carbon-supported silver complex electrocatalyst was dispersed in ethanol and sprayed onto a carbon paper substrate as the anode catalyst. A platinum sheet was used as the cathode, and an Ag / AgCl electrode was used as the reference electrode to construct a three-electrode system. Propylene gas was introduced into the electrolyte at a flow rate of 20 s·ccm, and the reaction was continuously stirred for 1 hour at a constant voltage of 1.8 V relative to the Ag / AgCl electrode.

[0185] Samples were taken and 1,2-propanediol was quantitatively identified using liquid chromatography. The results are as follows: Figure 12 As shown, the peak area of ​​1,2-propanediol is 22645.3, the Faraday efficiency of 1,2-propanediol is 37.4%, and the PG partial current density is 3.1 mA·cm⁻¹. -2 The reaction rate is 58.3 μmol·h⁻¹. -1 ·cm -2 In addition, the current-time curves for the electrocatalytic oxidation of propylene to 1,2-propanediol were measured, and the results are as follows: Figure 13 As shown, it can be seen that as the reaction proceeds, the reaction current first increases and then remains stable within 1 hour, but the overall current density is lower than that in Example 1.

[0186] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0187] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a polymer electrode with a metal molecular catalyst, characterized in that, The metal molecule catalyst polymer electrode comprises an anode catalyst substrate, a polymer formed by polymerization of heterocyclic organic ligand molecules, and an active metal coordinated with the polymer. The organic ligand molecules include polymerization units, linking units, and coordination units, and the organic ligand molecules form coordination bonds with the active metal through the coordination units to obtain a complex. The preparation method includes the following steps: S1: The synthesis of organic ligand monomers is achieved by connecting polymerization units and coordination units with saturated alkyl chains through nucleophilic substitution reactions. S2: Organic polymer electrode is obtained by oxidizing and polymerizing organic ligand monomers via electrochemical oxidation and loading them onto the surface of the anode catalyst substrate; S3: The organic polymer electrode is subjected to a coordination reaction with a metal salt solution to obtain a metal molecular catalyst polymer electrode.

2. The preparation method according to claim 1, characterized in that, The anode catalyst substrate includes one or more of the following: carbon cloth, carbon paper, nickel foam, nickel sheet, nickel mesh, copper foam, copper sheet, copper mesh, titanium sheet, titanium mesh, stainless steel sheet, stainless steel mesh, ITO conductive glass, and FTO conductive glass, preferably carbon cloth or carbon paper.

3. The preparation method according to claim 1 or 2, characterized in that, The polymerization unit includes one or more of thiophene, pyrrole, 3,4-ethylenedioxythiophene, furan, indole, aniline, 9-fluorenic acid, carbazole, and benzothiophene, preferably one or more of furan, indole, or carbazole; The coordination unit includes one or more of oxazoline ligands, Salen ligands, polypyridine ligands, phenanthroline ligands, and bipyridine ligands, preferably oxazoline ligands and / or bipyridine ligands; The saturated alkyl chain includes a straight-chain saturated alkyl chain of C1 to C10.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The active metal includes one or more of iron, cobalt, manganese, nickel, copper, silver, gold, iridium, palladium, and platinum, with silver and / or palladium being preferred.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The electrochemical oxidation method described in step S2 includes: in a separated cell, using an anode catalyst substrate as the anode, a cathode catalyst as the cathode, and a solution containing a supporting electrolyte as the electrolyte, adding the organic ligand monomer to the anode cell to carry out an oxidative polymerization reaction and loading it onto the surface of the anode catalyst substrate to obtain an organic polymer electrode; Preferably, the concentration of the organic ligand monomer is 0.005–0.015 mol / L; The electrolyte includes one or more of tetrabutylammonium perchlorate, tetrabutylammonium tetrafluoroborate, and tetrabutylammonium hexafluorophosphate in acetonitrile or dichloromethane solution, preferably a tetrabutylammonium perchlorate in acetonitrile solution; The cathode catalyst comprises one or more of platinum, gold, silver, ruthenium, iridium, palladium, copper, and rhodium, with platinum being preferred; The current density during the oxidative polymerization reaction is 0.1–2.5 mA / cm². 2 .

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step S3, the metal salt solution comprises an acetonitrile or dichloromethane solution of the metal salt. Preferably, the concentration of the metal salt solution is 5–15 mmol / L; The molar ratio of the active metal to the organic ligand molecule is 2:1 to 10:

1. In the aforementioned metal molecule catalyst polymer electrode, the loading of the active metal is 0.1–5 μmol / cm³. 2 .

7. A method for preparing 1,2-propanediol by propylene oxidation using an electropolymerization molecular catalyst, characterized in that the following... Steps: The metal molecular catalyst polymer electrode prepared by the preparation method according to any one of claims 1 to 6 is used as the anode, and the cathode catalyst is used as the cathode. The two are assembled into an electrolytic cell with an electrolyte aqueous solution. Propylene gas is introduced into the electrolytic cell under voltage conditions.

8. The method according to claim 7, characterized in that, The electrolytic cell also has a reference electrode, which is Ag / AgCl or Hg / Hg2Cl2, preferably Ag / AgCl; The voltage is 1V to 4V vs Ag / AgCl, preferably 1.4V to 2.0V vs Ag / AgCl, and more preferably 1.6V to 2.0V vs Ag / AgCl.

9. The method according to claim 7 or 8, characterized in that, The electrolyte aqueous solution includes one or more of the following: sodium sulfate, potassium sulfate, lithium sulfate, zinc sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, lithium nitrate, zinc nitrate, calcium nitrate, magnesium nitrate, aluminum nitrate, sulfuric acid, nitric acid, perchloric acid, sodium perchlorate, potassium perchlorate, and lithium perchlorate. Preferably, the concentration of the electrolyte aqueous solution is 1 mg / mL to 1000 mg / mL, more preferably 3 mg / mL to 20 mg / mL.

10. The method according to any one of claims 7 to 9, characterized in that, The flow rate of the propylene gas is 1 s.ccm to 500 s.ccm, preferably 10 s.ccm to 30 s.ccm.

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